These studies are designed to reveal the existence and extent of projections from the basal ganglia to the mesencephalic tegmentum. These studies have already established the existence of a direct projection from one of the major outputs of the basal ganglia, the entopeduncular nucleus, to the Mesencephalic Locomotor Region (MLR). This region is known to modulate locomotion oscillators located in the cervical and lumbar enlargements of the spinal cord. Proposed experiments for the following year hope to determine if another major output of the basal ganglia, the substantia nigra, also sends afferent projections to the MLR and adjacent areas. These experiments employ single unit recording techniques to identify antidromically activated neurons. In addition, the use of tritiated amino acids will reveal the distribution of downstream projections of the MLR.